An agricultural harvesting machine such as a combine includes a header and a feeder housing which remove the crop material from the field, gather the crop material and transport the crop material to a separator. The grain is cleaned and deposited in a grain tank. When the grain tank becomes full, an unloading auger which is positioned alongside the combine during harvesting is moved to the unloading position in which the auger extends approximately perpendicular to the longitudinal axis of the combine. The combine drives alongside a vehicle into which the grain is to be unloaded, such as a semi-trailer, and the unloading auger is actuated to discharge the grain into the vehicle.
For small stemmed crops such as wheat, soybeans, etc., the combine typically carries and drives a header, in this instance also known as a cutting platform, with a sickle bar cutter at the leading edge of the platform. The crop is cut using the sickle bar cutter and conveyed to the feeder housing of the combine using suitable conveying structures such as an overhead reel, draper belts or dual feed auger, etc.
For certain applications and operating environments, the crop is cut prior to full maturation and dry down, and allowed to dry in the field prior to being picked up and processed with a combine. A crop which is processed too green is hard on the internal workings of the combine and also results in high drying costs to reduce the crop moisture level to a target level.
For example, in western Canada a fair amount of cereal grain is grown where the growing seasons are typically too short to allow full maturation and dry down. It is thus common practice to first cut the cereal grain with a sickle bar cutter in windrows. The cereal grain is allowed to dry in the windrows and is subsequently picked up using a pickup header carried by the combine. A cutting platform with a sickle bar cutter as described above is not suitable for this type harvesting practice.
One type of known pickup header is a belt pickup header, including one or more belts which are carried by generally horizontally positioned drive and idler rollers. The belt(s) convey the crop material rearwardly to the feeder housing of the combine.
A belt pickup header can experience large and abrupt vertical motion when exposed to rough terrain or rough fields. The belt pickup is typically cantilevered in front of the header frame, which is itself cantilevered from the forward extending feeder housing on the front of the combine. Fast transportation speeds and rough road terrain can cause significant movement of the pickup belt header and in extreme situations, result in mechanical failure. Rough or uneven field terrain can also cause the belt pickup to lift off the ground and miss crop.
During transportation, at speeds higher than field operation, bumps or dips in the road terrain can result in the belt pickup being thrown vertically into the air resulting in damage to the belt pickup or to the header frame due to the abrupt stopping at the upper or lower stops. Thus, suspension is necessary for efficient and safe field operation and transportation of a belt pickup platform. During harvesting operation, the forward end of the belt pickup must follow the ground quite closely. Belt pickup headers are provided with a pair of wide-spaced gauge wheels running just ahead and outside of the forward portion of the belt pickup. The belt pickup is free to pivot relative to the header frame about a generally horizontal axis. A pair of tension springs extend at a downwardly angled orientation between the header frame and each respective end of the belt pickup to support the belt pickup when the header is raised, such as during road transport or at the ends of the windrows.
What is needed in the art is a suspension system for a belt pickup header which better vertically supports and damps movement of the belt pickup.